﻿using System;
using System.Data;
using System.IO;

namespace YG.CommonFuncs
{
    /// <summary>
    /// 数据转换成csv
    /// </summary>
    public static class Data2CSV
    {
        public static string GetColumnsByDataTable(DataTable dt)
        {
            string strColumns = null;

            if (dt.Columns.Count > 0)
            {
                //int columnNum = 0;
                //columnNum = dt.Columns.Count;
                for (int i = 0; i < dt.Columns.Count; i++)
                {
                    if (i == 0)
                    {
                        strColumns = dt.Columns[i].ColumnName;
                    }
                    else
                    {
                        strColumns += "," + dt.Columns[i].ColumnName;
                    }
                }
            }

            return strColumns;
        }

        /// <summary>
        /// 导出报表为Csv
        /// </summary>
        /// <param name="dt">DataTable</param>
        /// <param name="strFilePath">物理路径</param>
        /// <param name="tableheader">表头</param>
        /// <param name="columname">字段标题,逗号分隔</param>
        public static string DataTableToCSV(DataTable dt, string strFilePath)
        //public static bool DataTableToCsv(DataTable dt, string strFilePath, string tableheader, string columname)

        {
            try
            {
                string columname = GetColumnsByDataTable(dt);

                string strBufferLine = "";
                StreamWriter strmWriterObj = new StreamWriter(strFilePath, false, System.Text.Encoding.UTF8);

                //StreamWriter strmWriterObj = new StreamWriter(strFilePath);
                //strmWriterObj.WriteLine(tableheader);
                strmWriterObj.WriteLine(columname);
                for (int i = 0; i < dt.Rows.Count; i++)
                {
                    strBufferLine = "";
                    for (int j = 0; j < dt.Columns.Count; j++)
                    {
                        if (j > 0)
                            strBufferLine += ",";
                        strBufferLine += dt.Rows[i][j].ToString();
                    }
                    strmWriterObj.WriteLine(strBufferLine);
                }
                strmWriterObj.Close();
                return strFilePath;
            }
            catch (Exception ex)
            {
                return "";
            }
        }

        public static string DataSetToCSV(DataSet dS, string strFilePath, int index)
        //public static bool DataTableToCsv(DataTable dt, string strFilePath, string tableheader, string columname)

        {
            try
            {
                string columname = GetColumnsByDataTable(dS.Tables[index]);

                string strBufferLine = "";
                StreamWriter strmWriterObj = new StreamWriter(strFilePath, false, System.Text.Encoding.UTF8);

                //StreamWriter strmWriterObj = new StreamWriter(strFilePath);
                //strmWriterObj.WriteLine(tableheader);
                strmWriterObj.WriteLine(columname);
                for (int i = 0; i < dS.Tables[index].Rows.Count; i++)
                {
                    strBufferLine = "";
                    for (int j = 0; j < dS.Tables[index].Columns.Count; j++)
                    {
                        if (j > 0)
                            strBufferLine += ",";
                        strBufferLine += dS.Tables[index].Rows[i][j].ToString();
                    }
                    strmWriterObj.WriteLine(strBufferLine);
                }
                strmWriterObj.Close();
                return strFilePath;
            }
            catch (Exception ex)
            {
                return "";
            }
        }

        public static string DataSetToCSV(DataSet dS, string strFilePath, string TableName)
        {
            try
            {
                string columname = GetColumnsByDataTable(dS.Tables[TableName]);

                string strBufferLine = "";
                StreamWriter strmWriterObj = new StreamWriter(strFilePath, false, System.Text.Encoding.UTF8);

                //StreamWriter strmWriterObj = new StreamWriter(strFilePath);
                //strmWriterObj.WriteLine(tableheader);
                strmWriterObj.WriteLine(columname);
                for (int i = 0; i < dS.Tables[TableName].Rows.Count; i++)
                {
                    strBufferLine = "";
                    for (int j = 0; j < dS.Tables[TableName].Columns.Count; j++)
                    {
                        if (j > 0)
                            strBufferLine += ",";
                        strBufferLine += dS.Tables[TableName].Rows[i][j].ToString();
                    }
                    strmWriterObj.WriteLine(strBufferLine);
                }
                strmWriterObj.Close();
                return strFilePath;
            }
            catch (Exception ex)
            {
                return "";
            }
        }

        /// <summary>
        /// 将Csv读入DataTable
        /// </summary>
        /// <param name="filePath">csv文件路径</param>
        /// <param name="n">表示第n行是字段title,第n+1行是记录开始</param>
        public static DataTable CSVToDataTable(string filePath, int n, DataTable dt)
        {
            StreamReader reader = new StreamReader(filePath, System.Text.Encoding.UTF8, false);
            int i, m = 0;
            reader.Peek();
            while (reader.Peek() > 0)
            {
                m += 1;
                string str = reader.ReadLine();
                if (m >= n + 1)
                {
                    string[] split = str.Split(',');

                    System.Data.DataRow dr = dt.NewRow();
                    for (i = 0; i < split.Length; i++)
                    {
                        dr[i] = split[i];
                    }
                    dt.Rows.Add(dr);
                }
            }
            return dt;
        }
    }
}